Structure for fine blanking

ABSTRACT

The structure for fine blanking includes opposed die members one of which is supported by a hydraulic cushion, a die pad supported by a separate hydraulic cushion in an opening in the other die member and a blanking punch opposed to the die pad and having substantially the same dimension as the opening in the one die member positioned within the other die member. A gripping ring is provided on one of the die members at the periphery of a blank to be cut thereby. Piercing punches are provided extending through the die pad and operate in conjunction with piercing pads supported on the hydraulic cushion supporting the one die member. Separate hydraulic delay structure is provided in conjunction with both of the hydraulic cushions. The fine-blanking method disclosed includes moving the die members toward each other to clamp a metal workpiece tightly about the periphery of a blank to be cut therefrom whereby the gripping ring forces the metal of the workpiece inwardly toward the periphery of the blank to be cut therefrom, cutting the blank between the blanking punch and other die member with substantially no clearance therebetween, and piercing the blank. The die members are then moved away from each other and the slugs pierced from the blank and the cut blanks are sequentially ejected from the upper die member and the blanking punch in accordance with selected separate delay times.

United States Patent [72] Inventors Ervin E. Wolnosky Troy; Waldemar Holz, Redford Township, Wayne County, Mich. [211 Appl. No. 768,698 [22] Filed Oct. 18, 1968 [45] Patented Mai-.16, 1971 [73} Assignee Di-Dro Systems Inc.

Dearborn, Mich.

[54] STRUCTURE FOR FINE BLANKING 10 Claims, 1 Drawing Fig. [52] U.S. Cl 83/124, 83/132, 83/137, 83/390, 83/639 [51] Int. Cl B26d 7/02, B26d 7/06 [50] Field ofSearch 83/14,123, 125,124,137,132, 390, 639, 681

[56] References Cited UNITED STATES PATENTS 1,428,174 9/1922 Luther 83/124 2,579,940 12/1951 Lobrovich. 83/137X 3,107,567 10/1963 Lindner 83/124 3,111,053 11/1963 Svensson... 83/125X 3,119,292 l/1964 Schmid 83/137X Primary Examiner Frank T. Yost Attorney-Whittemore, Hulbert & Belknap ABSTRACT: The structure for fine blanking includes opposed die members one of which is supported by a hydraulic cushion, a die pad supported by a separate hydraulic cushion in an opening in the other die member and a blanking punch opposed to the die pad and having substantially the same dimension as the opening in the one die member positioned within the other die member. A gripping ring is provided on one of the die members at the periphery of a blank to be cut thereby. Piercing punches are provided extending through the die pad and operate in conjunction with piercing pads supported on the hydraulic cushion supporting the one die member. Separate hydraulic delay structure is provided in conjunction with both of the hydraulic cushions.

The fine-blanking method disclosed includes moving the die I members toward each other to clamp a metal workpiece tightly about the periphery of a blank to be cut therefrom whereby the gripping ring forces the metal of the workpiece inwardly toward the periphery of the blank to be cut therefrom, cutting the blank between the blanking punch and other die member with substantially no clearance therebetween, and piercing the blank. The die members are then moved away from each other and the slugs pierced from the blank and the cut blanks are sequentially ejected from the upper die member and the blanking punch in accordance with selected separate delay times.

Patented March 16,1971

INVENTORS ERVIN E. WOLNOSKY WALDEMAR HOLZ ATTOR N EYS STRUCTURE FOR FINE BLANKING BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to stamping of metal parts and refers more specifically to structure for an a method of fine-blanking metal parts to produce a finished part in a single press stroke having parallel edges of exact dimensions and a desired finish without secondary operations. More particularly, the field of the invention includes a method of securing the periphery of a blank to be cut from a metal workpiece between a pair of die members including an opening and a punch having substantially no clearance therebetween, forcing metal inwardly toward the periphery of the blank to be cut from the workpiece prior to cutting of the blank, piercing the blank under predetermined pressure and sequentially ejecting slugs pierced from the blank and the cut blank from the punch and die at selected times.

2. Description of the Prior Art In the past, blanks have been stamped from metal workpieces between punches and dies having substantial clearance therebetween. With such stamping operations, the blank is usually broken away from the workpiece over a portion of the sheared edge so that the edges are rough and the blanks are not to the tolerance required of many finished parts. Consequently to provide finished parts having desired tolerances and edge conditions secondary finishing operations such as shaving or otherwise machining the parts have in the past been necessary. The finishing operations are often slower and more costly than the initial blanking operation.

Prior attempts to eliminate the edge condition on blanks due to, for example, die break, have included the use of special shaving presses having a vibratory movement and special shaving tools. In most cases such shaving tools require high production to justify the initial expense thereof. Shaving stations have also been built into progressive dies. However, the maintenance of tolerances" using such structure is practically impossible.

SUMMARY OF THE INVENTION In accordance with the invention, structure for fine blanking is provided including opposed die members for firmly gripping a workpiece about the periphery of a blank to be cut therefrom one of g which is supported by a first hydraulic cushion and includes a gripping ring for urging the material of the workpiece inwardly of the periphery of the blank, a die pad supported by a second hydraulic cushion positioned within the other of the die members, a blanking punch positioned within the one die member supported by means of a second hydraulic cushion, aligned with the die pad and having substantially no clearance with the other die member for cutting a blank from a workpiece in conjunction with the one die member with the blank under pressure provided by the pad, die members and gripping ring. Piercing punches are also provided in accordance with the invention extending through the die pad operable in conjunction with piercing pads supported by the first hydraulic cushion for piercing slugs from the blank.

The hydraulic cushion structures provide desired clamping and cutting pressures during operation of the blanking structure. In addition, hydraulic delay structure is included in the cushion structures to permit sequential ejection of the cut blank and pierced slugs at selected times during separation of the die members.

The method of the invention includes the clamping of a workpiece about the periphery of a blank to be cut therefrom under a pressure established by a hydraulic cushion, urging the metal of the workpiece at the periphery of the blank to be cut inwardly of the blank to be cut, cutting the blank between a punch and die member between which there is substantially no clearance, piercing the blank at a pressure determined by another hydraulic cushion and ejecting the slugs and blanks sequentially to provide a finished part having parallel edges of exact dimension and desired finish.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a partly schematic, partly diagrammatic broken vertical section view of fine blanking structure constructed in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in the FIGURE, the structure for fine blanking of metal workpieces 110 includes a lower riser I2 and an upper riser 14 adapted to be secured to the bed and ram of a press respectively for movement toward and away from each other under high pressure of, for example, 100,000 pounds at, for example, 25 strokes per minute. A lower die shoe I6 is secured to the lower riser 12 and an upper die shoe 1% is secured to the upper riser 14. The posts 20 and bearings 22 are provided between the lower and upper die shoes 16 and 18 as shown in the usual manner to provide accurate movement of the die shoes 16 and 18 toward and away from each other.

A lower die member 241 is secured to the die shoe 116 by the clamping ring 26 and bolts 28. The lower die member 24 is supported by the hydraulic cushion 30 for movement toward and away from the die shoe 16 permitted by the annular recess 31 in the clamping ring 26 and the flange 32 on the die member 24. The upper die member 34 is rigidly secured to the upper die shoe ,18 by convenient means such as the bolts 36.

As shown, the die members 24 and 34 are opposed whereby on movement of the die shoes 16 and 18 toward each other the workpiece 38 is securely clamped therebetween about the periphery of a blank 40 to be cut therefrom. In addition, a gripping ring 42 having a V-shaped cross section is provided on the lower die member surrounding the blank to be cut from the workpiece 38 whereby the metal at the periphery of the blank is urged inwardly toward the blank on clamping of the workpiece 38 between the die members 24 and 34.

A blank punch 44 is secured to the lower die shoe 16 by convenient means such as the bolt 46. The punch 44 is carefully machined to provide substantially no clearance between the punch 44 and the cutting edge 48 of the die member 34.

The die pad 50 is mounted for reciprocal movement within the die member 34 and is supported on the cushion structure 52. Piercing punches 5t extend through the die pad 50 in opposition to the piercing pads 56 which are also supported on the cushion structure 30 for reciprocal movement in the punch 44.

The cushion structure 30 includes the hydraulic cylinder 58 by which the piston 60 having the cushion pad 62 thereon is supported in accordance with the pressure on hydraulic fluid fed thereto through the hydraulic line 64. The cylinders 66 and 68 transfer forces between the piercing pads 56 and the lower die member 24 and the cushion pad 62.

The hydraulic circuit 70 supplies hydraulic fluid under pressure to conduit 64 and includes a tank 72 for storage of hydraulic fluid under pressure, check valve 74 through which hydraulic fluid is supplied to the cylinder 30 from tank 72, unloading valve 76 and pilot valve 78 for relieving the pressure in the cylinder 30 at a selected pressure and the delay valve 80 for determining the time delay for return of fluid to the cylinder 30 after fluid has been forced therefrom due to closing of the die members 24 and 34 including delay adjusting means 82. The circuit 70 is considered in detail in U.S. Pat. No. Re. 25,072 and will not therefore be considered in detail herein. The function of this hydraulic circuit in fine blanking will, however, be considered in the operation of the structure 10.

The hydraulic cushion 52 is similar to the hydraulic cushion 30 and includes a cushion pad 84 supported by piston 86 within cylinder 8% and the hydraulic circuit 90 including the tank 92, delay valve 94 having the adjusting means 96 for ad justing the time delay thereof, the check valve 98, unloading valve 100, and pilot valve 102 for controlling the hydraulic fluid fed through the conduit 104 to or from the cylinder 88. The die pad 50 is supported on the cushion pad 84 by the cylinders 106. V

Guide means 108 including the spring 110 for clamping the workpiece 38 between a movable guide 112 and a fixed guide 114 is provided at the left of the die members 24 and 34 to guide the workpiece.

At the right of the die members 24 and 34 a scrap cutter is provided including a lower cutting die 116 secured to the bottom die shoe 16 by bolt 118, upper cutting die 120 secured to the upper die shoe 18 by bolt 122 and guide 124 resiliently urged into engagement with the workpiece 38 by the spring 126.

In overall operation of the fine blanking structure the workpiece 38 is fed through the guide means 108 between the die members 24 and 34 from left to right of the blanking structure 10 as shown in the FIGURE of the drawings. At this time the die shoes 16 and 18 are apart, the pistons 60 and 86 are extended under pressure from the tanks 72 and 92 through the check valves 74 and 98 whereby the pads 62 and 84 are extended and the die members 24 and 34 are flush with die pad 50 and punch 44.

The die shoes 16 and 18 are then moved toward each other whereby the workpiece 38 is firmly clamped between the die members 24 and 34 outside of the periphery of the blank 40 to be cut therefrom at a pressure determined by cushion structure 30. The metal workpiece is engaged by the gripping ring 42 on the die member 24 whereby the metal thereof is forced inwardly around the periphery of the blank 40 to be cut.

On continued movement of the die shoes 16 and 18 toward each other, the cushion 52 unloads through the unloading valve 100 aided by the pilot valve 102 whereby the die pad 50 moves upward to the position illustrated in the FIGURE so that the blank 40 is cut by the punch 44 under pressure provided by the cushion structure 52. In addition, the slugs 128 are pierced from the blank 40 by the piercing punches 54 under pressure provided by the cushion structure 30. The cushion structure 30 unloads through the unloading valve 76 aided by the pilot valve 78. At the same time, the scrap 130 is cut by the scrap cutter structure.

When the die members 24 and 34 are moved away from each other subsequently, the return of the die pad 50 on filling of the cylinder 88 of the cushion structure 52 through the pad delay valve 94 and the check valve 98 is delayed for a time determined by the setting of the delay adjustment 96 of the delay valve 94. Similarly, the return of the piercing pad 56 to a position wherein the slugs 128 are ejected from the punch 44 is delayed by the setting of the delay adjustment 82 of the delay valve 80. Thus, the ejection of the slugs 128 and blank 40 may be sequenced in operation so that they may be easily removed and the workpiece 38 again indexed without interference with each other.

The blank produced by such operation has parallel particularly smooth edges with no die break. In addition, due to the forming under pressure from the punch 44 and die pad 50 the formed blank has particularly good flatness, and the substantial absence of clearance between the punch and the upper die member 34 provides absolute dimensional tolerance for the finished blank.

While one embodiment of the invention has been considered in detail, it will be understood that other embodiments and modifications of the structure for and method of fine blanking disclosed are contemplated by the inventors. It is, therefore, the intention to include all modifications and embodiments as are defined by the appended claims within the scope of the invention.

We claim:

1. Fine-blanking structure comprising opposed die members adapted to receive a workpiece therebetween from which a blank is to be cut, an opposed blanking punch and die pad operably associated with the die members, said blanking punch and one of said die members providing substantially no clearance therebetween in the closed position thereof, hydraulic cushion structure supporting at least one of said die members and at least one of said punch and die pad, means for moving the die members and the punch and die pad toward and away from each other whereby the workpiece exterior to the blank to be cut therefrom may be held under high pressure during cutting of the blank by the punch in cooperation with one of the die members, first delay means operably associated with the die pad for preventing ejection of a cut blank for a predetermined time after the die members have been moved away from each other subsequent to cutting a die blank from the workpiece, at least one piercing punch extending through the die pad and a piercing pad extending through the punch operably associated with the die members whereby a blank being cut may be pierced and second delay means operably associated with the piercing pad for delaying the ejection of slugs cut from the blank.

2. Structure as set forth in claim 1 and further including means for separately varying the length of the delay provided by the delay means to sequence the ejection of the cut blank and the slugs cut from the blank.

3. Structure as set forth in claim 2, wherein the delay mean are hydraulic.

4. Structure as set forth in claim 2 wherein the means for separately varying the length of the delay includes means for making the first delay longer than the delay provided by the second delay means.

5. Structure as set forth in claim 2 wherein the means for separately varying the length of the delay includes means for making the second delay longer than the delay provided by the first delay means.

6. Structure as set forth in claim 1 and further including means operably associated with at least one of the die members for urging the metal of the workpiece at the periphery of the blank toward the blank on clamping of the workpiece between the die members.

7. Structure as set forth in claim 6 wherein the means for urging the metal of the workpiece at the periphery of the blank toward the blank on clamping of the workpiece between the die members includes a gripping ring having a V-shaped cross section on the one die member surrounding the blank to be cut from the workpiece.

8. Fine-blanking structure comprising opposed die members adapted to receive a workpiece therebetween from which a blank is to be cut, an opposed blanking punch and die pad operably associated with the die members, said blanking punch and one of said die members providing substantially no clearance therebetween in the closed position thereof, hydraulic cushion structure supporting at least one of said die members and at least one of said punch and die pad, means for moving the die members and the punch and die pad toward and away from each other whereby the workpiece exterior to the blank to be cut therefrom may be held under high pressure during cutting of the blank by the punch in cooperation with one of the die members, first delay means operably associated with the die pad for preventing ejection of a cut blank for a predetermined time after the die members have been moved away from each other subsequent to cutting a die blank from the workpiece, at least one piercing punch extending through the die pad and a piercing pad extending through the punch operably associated with the die members whereby a blank being cut may be pierced, second delay means operably associated with the piercing pad for delaying the ejection of slugs cut from the blank, a gripping ring having a V-shaped cross section on one ofthe die members surrounding the blank to be cut from the workpiece for urging the metal of the workpiece at the periphery of the blank toward the blank on clamping of the workpiece between the members and means for separately varying the length of the delay provided by the delay means to sequence the ejection of the cut blank and the slugs cut from the blank.

9. Structure as set forth in claim 8 wherein the means for separately varying the length of the delay includes means for making the first delay longer than the delay provided by the second delay means.

10. Structure as set forth in claim 8 wherein the means for epar e va yin e mstheitbe delay qls d means for making the second delay longer than the delay provided by the first delay means. 

1. Fine-blanking structure comprising opposed die members adapted to receive a workpiece therebetween from which a blank is to be cut, an opposed blanking punch and die pad operably associated with the die members, said blanking punch and one of said die members providing substantially no clearance therebetween in the closed position thereof, hydraulic cushion structure supporting at least one of said die members and at least one of said punch and die pad, means for moving the die members and the punch and die pad toward and away from each other whereby the workpiece exterior to the blank to be cut therefrom may be held under high pressure during cutting of the blank by the punch in cooperation with one of the die members, first delay means operably associated with the die pad for preventing ejection of a cut blank for a predetermined time after the die members have been moved away from each other subsequent to cutting a die blank from the workpiece, at least one piercing punch extending through the die pad and a piercing pad extending through the punch operably associated with the die members whereby a blank being cut may be pierced and second delay means operably associated with the piercing pad for delaying the ejection of slugs cut from the blank.
 2. Structure as set forth in claim 1 and further including means for separately varying the length of the delay provided by the delay means to sequence the ejection of the cut blank and the slugs cut from the blank.
 3. Structure as set forth in claim 2, wherein the delay means are hydraulic.
 4. Structure as set forth in claim 2 wherein the means for separately varying the length of the delay includes means for making the first delay longer than the delay provided by the second delay means.
 5. Structure as set forth in claim 2 wherein the means for separately varying the length of the delay includes means for making the second delay longer than the delay provided by the first delay means.
 6. Structure as set forth in claim 1 and further including means operably associated with at least one of the die members for urging the metal of the workpiece at the periphery of the blank toward the blank on clamping of the workpiece between the die members.
 7. Structure as set forth in claim 6 wherein the means for urging the metal of the workpiece at the periphery of the blank toward the blank on clamping of the wOrkpiece between the die members includes a gripping ring having a V-shaped cross section on the one die member surrounding the blank to be cut from the workpiece.
 8. Fine-blanking structure comprising opposed die members adapted to receive a workpiece therebetween from which a blank is to be cut, an opposed blanking punch and die pad operably associated with the die members, said blanking punch and one of said die members providing substantially no clearance therebetween in the closed position thereof, hydraulic cushion structure supporting at least one of said die members and at least one of said punch and die pad, means for moving the die members and the punch and die pad toward and away from each other whereby the workpiece exterior to the blank to be cut therefrom may be held under high pressure during cutting of the blank by the punch in cooperation with one of the die members, first delay means operably associated with the die pad for preventing ejection of a cut blank for a predetermined time after the die members have been moved away from each other subsequent to cutting a die blank from the workpiece, at least one piercing punch extending through the die pad and a piercing pad extending through the punch operably associated with the die members whereby a blank being cut may be pierced, second delay means operably associated with the piercing pad for delaying the ejection of slugs cut from the blank, a gripping ring having a V-shaped cross section on one of the die members surrounding the blank to be cut from the workpiece for urging the metal of the workpiece at the periphery of the blank toward the blank on clamping of the workpiece between the members and means for separately varying the length of the delay provided by the delay means to sequence the ejection of the cut blank and the slugs cut from the blank.
 9. Structure as set forth in claim 8 wherein the means for separately varying the length of the delay includes means for making the first delay longer than the delay provided by the second delay means.
 10. Structure as set forth in claim 8 wherein the means for separately varying the length of the delay includes means for making the second delay longer than the delay provided by the first delay means. 